The present invention relates to a valve box manifold system and a method for distributing a chemical through valve manifolds to a plurality of points of use. More particularly, the present invention relates to such a system and method in which a fluid circuit is arranged such that the valve manifolds are fed with the chemical at opposite ends thereof and pairs of isolation valves, located within the fluid circuit, are positioned to selectively isolate each of the valve manifolds independently of the remaining valve manifolds.
It is often necessary to distribute chemical to a series of points of use located within an industrial facility. For instance, in a semiconductor manufacturing facility, chemicals such as photo-resist, slurries, hydrofluoric acid, hydrogen peroxide, ammonium hydroxide, and etc., are distributed to various tools used in the manufacture of the semiconductors. Typically, a dispense unit, that can be one or more pumps or pressure vessels, induces fluid flow through a fluid circuit having a series of valve manifolds that are used to connect groups of tools to the fluid circuit. The fluid circuit is provided with valve boxes to enclose the valve manifolds and double walled pipe is used throughout. As a result, any leakage from either the piping or the valve manifolds is deposited into the valve boxes which thereby serve to contain the leakage.
Typically, flow within the fluid circuit is automatically controlled by computerized control systems which act to remotely activate valves within the valve manifold upon demand of chemical from the tools. Detectors are located within the valve boxes to sense leaks and thereby cause closure of isolation valves located at opposite ends of the valve manifolds and the dispense system to shut down. A problem of such an arrangement resides in the design of the fluid circuit. The valve manifolds and valve boxes are arranged in series along the fluid circuit and the fluid circuit is fed at one end from a controlled dispense unit. Thus, in the event that a leak is sensed from one valve box, all valve manifolds and therefore all tools are shut off whether on not there is any leakage other than that at the valve box at which the leak was sensed.
As a result, tools are needlessly taken out of service producing expensive production delays. Moreover, the feeding of valve manifolds at one end leaves very little flexibility on the amount of flow that can be introduced into each tool.
As will be discussed, the present invention provides a valve manifold box system that has an improved fluid circuit to allow individual valve boxes to be taken off line for maintenance or when leaks are detected and further allows for more chemical to be introduced into each manifold.